In the recent years, biometric characteristics recognition has developed rapidly. A person's identity is recognized based on the individual biometric characteristics. It has gradually become very commonly used in many fields. Common biometric characteristics recognition such as facial characteristics recognition and fingerprint recognition have limitation in usage. Fingerprint can be easily forged, and is often affected by external factors because of frequent contact with the external environment. As a result, the fingerprint is changed and therefore cannot be recognized correctly. As for facial characteristics recognition, its low between-class variation causes poor recognition result. Besides, facial characteristics can also change due to the influence of external factors. Biometric characteristics recognition by using iris of human eyeball has high between-class variation and provides excellent result. External factors have insignificant influence on the recognition and therefore the accuracy is enhanced. No contact is required in the process of sampling. All these reasons help iris recognition to gain popularity in the recent years. The design of having iris recognition device directly installed on eyeglasses is already existed. Iris recognition can be processed directly by wearing eyeglasses. This allows a user's identity to be recognized by eyeglasses.
However, it is not easy to sample iris characteristics information by using the conventional iris recognition device installed on eyeglasses because of the limited distance between the eyeball and the eyeglasses. Therefore, it is a common problem of how to obtain effective and correct iris image for comparing and recognizing information.